1 //===- LowerInvoke.cpp - Eliminate Invoke & Unwind instructions -----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This transformation is designed for use by code generators which do not yet
11 // support stack unwinding. This pass supports two models of exception handling
12 // lowering, the 'cheap' support and the 'expensive' support.
14 // 'Cheap' exception handling support gives the program the ability to execute
15 // any program which does not "throw an exception", by turning 'invoke'
16 // instructions into calls and by turning 'unwind' instructions into calls to
17 // abort(). If the program does dynamically use the unwind instruction, the
18 // program will print a message then abort.
20 // 'Expensive' exception handling support gives the full exception handling
21 // support to the program at the cost of making the 'invoke' instruction
22 // really expensive. It basically inserts setjmp/longjmp calls to emulate the
23 // exception handling as necessary.
25 // Because the 'expensive' support slows down programs a lot, and EH is only
26 // used for a subset of the programs, it must be specifically enabled by an
29 // Note that after this pass runs the CFG is not entirely accurate (exceptional
30 // control flow edges are not correct anymore) so only very simple things should
31 // be done after the lowerinvoke pass has run (like generation of native code).
32 // This should not be used as a general purpose "my LLVM-to-LLVM pass doesn't
33 // support the invoke instruction yet" lowering pass.
35 //===----------------------------------------------------------------------===//
37 #define DEBUG_TYPE "lowerinvoke"
38 #include "llvm/Transforms/Scalar.h"
39 #include "llvm/Constants.h"
40 #include "llvm/DerivedTypes.h"
41 #include "llvm/Instructions.h"
42 #include "llvm/Intrinsics.h"
43 #include "llvm/LLVMContext.h"
44 #include "llvm/Module.h"
45 #include "llvm/Pass.h"
46 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/ADT/SmallVector.h"
49 #include "llvm/ADT/Statistic.h"
50 #include "llvm/Support/CommandLine.h"
51 #include "llvm/Target/TargetLowering.h"
56 STATISTIC(NumInvokes, "Number of invokes replaced");
57 STATISTIC(NumUnwinds, "Number of unwinds replaced");
58 STATISTIC(NumSpilled, "Number of registers live across unwind edges");
60 static cl::opt<bool> ExpensiveEHSupport("enable-correct-eh-support",
61 cl::desc("Make the -lowerinvoke pass insert expensive, but correct, EH code"));
64 class LowerInvoke : public FunctionPass {
65 // Used for both models.
68 // Used for expensive EH support.
70 GlobalVariable *JBListHead;
71 Constant *SetJmpFn, *LongJmpFn, *StackSaveFn, *StackRestoreFn;
72 bool useExpensiveEHSupport;
74 // We peek in TLI to grab the target's jmp_buf size and alignment
75 const TargetLowering *TLI;
78 static char ID; // Pass identification, replacement for typeid
79 explicit LowerInvoke(const TargetLowering *tli = NULL,
80 bool useExpensiveEHSupport = ExpensiveEHSupport)
81 : FunctionPass(ID), useExpensiveEHSupport(useExpensiveEHSupport),
83 initializeLowerInvokePass(*PassRegistry::getPassRegistry());
85 bool doInitialization(Module &M);
86 bool runOnFunction(Function &F);
88 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
89 // This is a cluster of orthogonal Transforms
90 AU.addPreserved("mem2reg");
91 AU.addPreservedID(LowerSwitchID);
95 bool insertCheapEHSupport(Function &F);
96 void splitLiveRangesLiveAcrossInvokes(SmallVectorImpl<InvokeInst*>&Invokes);
97 void rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
98 AllocaInst *InvokeNum, AllocaInst *StackPtr,
99 SwitchInst *CatchSwitch);
100 bool insertExpensiveEHSupport(Function &F);
104 char LowerInvoke::ID = 0;
105 INITIALIZE_PASS(LowerInvoke, "lowerinvoke",
106 "Lower invoke and unwind, for unwindless code generators",
109 char &llvm::LowerInvokePassID = LowerInvoke::ID;
111 // Public Interface To the LowerInvoke pass.
112 FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI) {
113 return new LowerInvoke(TLI, ExpensiveEHSupport);
115 FunctionPass *llvm::createLowerInvokePass(const TargetLowering *TLI,
116 bool useExpensiveEHSupport) {
117 return new LowerInvoke(TLI, useExpensiveEHSupport);
120 // doInitialization - Make sure that there is a prototype for abort in the
122 bool LowerInvoke::doInitialization(Module &M) {
123 const Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
124 if (useExpensiveEHSupport) {
125 // Insert a type for the linked list of jump buffers.
126 unsigned JBSize = TLI ? TLI->getJumpBufSize() : 0;
127 JBSize = JBSize ? JBSize : 200;
128 Type *JmpBufTy = ArrayType::get(VoidPtrTy, JBSize);
130 JBLinkTy = StructType::createNamed(M.getContext(), "llvm.sjljeh.jmpbufty");
131 Type *Elts[] = { JmpBufTy, PointerType::getUnqual(JBLinkTy) };
132 JBLinkTy->setBody(Elts);
134 const Type *PtrJBList = PointerType::getUnqual(JBLinkTy);
136 // Now that we've done that, insert the jmpbuf list head global, unless it
138 if (!(JBListHead = M.getGlobalVariable("llvm.sjljeh.jblist", PtrJBList))) {
139 JBListHead = new GlobalVariable(M, PtrJBList, false,
140 GlobalValue::LinkOnceAnyLinkage,
141 Constant::getNullValue(PtrJBList),
142 "llvm.sjljeh.jblist");
145 // VisualStudio defines setjmp as _setjmp
146 #if defined(_MSC_VER) && defined(setjmp) && \
147 !defined(setjmp_undefined_for_msvc)
148 # pragma push_macro("setjmp")
150 # define setjmp_undefined_for_msvc
153 SetJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::setjmp);
155 #if defined(_MSC_VER) && defined(setjmp_undefined_for_msvc)
156 // let's return it to _setjmp state
157 # pragma pop_macro("setjmp")
158 # undef setjmp_undefined_for_msvc
161 LongJmpFn = Intrinsic::getDeclaration(&M, Intrinsic::longjmp);
162 StackSaveFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
163 StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
166 // We need the 'write' and 'abort' functions for both models.
167 AbortFn = M.getOrInsertFunction("abort", Type::getVoidTy(M.getContext()),
172 bool LowerInvoke::insertCheapEHSupport(Function &F) {
173 bool Changed = false;
174 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
175 if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
176 SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
177 // Insert a normal call instruction...
178 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
180 NewCall->takeName(II);
181 NewCall->setCallingConv(II->getCallingConv());
182 NewCall->setAttributes(II->getAttributes());
183 NewCall->setDebugLoc(II->getDebugLoc());
184 II->replaceAllUsesWith(NewCall);
186 // Insert an unconditional branch to the normal destination.
187 BranchInst::Create(II->getNormalDest(), II);
189 // Remove any PHI node entries from the exception destination.
190 II->getUnwindDest()->removePredecessor(BB);
192 // Remove the invoke instruction now.
193 BB->getInstList().erase(II);
195 ++NumInvokes; Changed = true;
196 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
197 // Insert a call to abort()
198 CallInst::Create(AbortFn, "", UI)->setTailCall();
200 // Insert a return instruction. This really should be a "barrier", as it
202 ReturnInst::Create(F.getContext(),
203 F.getReturnType()->isVoidTy() ?
204 0 : Constant::getNullValue(F.getReturnType()), UI);
206 // Remove the unwind instruction now.
207 BB->getInstList().erase(UI);
209 ++NumUnwinds; Changed = true;
214 /// rewriteExpensiveInvoke - Insert code and hack the function to replace the
215 /// specified invoke instruction with a call.
216 void LowerInvoke::rewriteExpensiveInvoke(InvokeInst *II, unsigned InvokeNo,
217 AllocaInst *InvokeNum,
218 AllocaInst *StackPtr,
219 SwitchInst *CatchSwitch) {
220 ConstantInt *InvokeNoC = ConstantInt::get(Type::getInt32Ty(II->getContext()),
223 // If the unwind edge has phi nodes, split the edge.
224 if (isa<PHINode>(II->getUnwindDest()->begin())) {
225 SplitCriticalEdge(II, 1, this);
227 // If there are any phi nodes left, they must have a single predecessor.
228 while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
229 PN->replaceAllUsesWith(PN->getIncomingValue(0));
230 PN->eraseFromParent();
234 // Insert a store of the invoke num before the invoke and store zero into the
235 // location afterward.
236 new StoreInst(InvokeNoC, InvokeNum, true, II); // volatile
238 // Insert a store of the stack ptr before the invoke, so we can restore it
239 // later in the exception case.
240 CallInst* StackSaveRet = CallInst::Create(StackSaveFn, "ssret", II);
241 new StoreInst(StackSaveRet, StackPtr, true, II); // volatile
243 BasicBlock::iterator NI = II->getNormalDest()->getFirstNonPHI();
245 new StoreInst(Constant::getNullValue(Type::getInt32Ty(II->getContext())),
246 InvokeNum, false, NI);
248 Instruction* StackPtrLoad = new LoadInst(StackPtr, "stackptr.restore", true,
249 II->getUnwindDest()->getFirstNonPHI()
251 CallInst::Create(StackRestoreFn, StackPtrLoad, "")->insertAfter(StackPtrLoad);
253 // Add a switch case to our unwind block.
254 CatchSwitch->addCase(InvokeNoC, II->getUnwindDest());
256 // Insert a normal call instruction.
257 SmallVector<Value*,16> CallArgs(II->op_begin(), II->op_end() - 3);
258 CallInst *NewCall = CallInst::Create(II->getCalledValue(),
260 NewCall->takeName(II);
261 NewCall->setCallingConv(II->getCallingConv());
262 NewCall->setAttributes(II->getAttributes());
263 NewCall->setDebugLoc(II->getDebugLoc());
264 II->replaceAllUsesWith(NewCall);
266 // Replace the invoke with an uncond branch.
267 BranchInst::Create(II->getNormalDest(), NewCall->getParent());
268 II->eraseFromParent();
271 /// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
272 /// we reach blocks we've already seen.
273 static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
274 if (!LiveBBs.insert(BB).second) return; // already been here.
276 for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
277 MarkBlocksLiveIn(*PI, LiveBBs);
280 // First thing we need to do is scan the whole function for values that are
281 // live across unwind edges. Each value that is live across an unwind edge
282 // we spill into a stack location, guaranteeing that there is nothing live
283 // across the unwind edge. This process also splits all critical edges
284 // coming out of invoke's.
286 splitLiveRangesLiveAcrossInvokes(SmallVectorImpl<InvokeInst*> &Invokes) {
287 // First step, split all critical edges from invoke instructions.
288 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
289 InvokeInst *II = Invokes[i];
290 SplitCriticalEdge(II, 0, this);
291 SplitCriticalEdge(II, 1, this);
292 assert(!isa<PHINode>(II->getNormalDest()) &&
293 !isa<PHINode>(II->getUnwindDest()) &&
294 "critical edge splitting left single entry phi nodes?");
297 Function *F = Invokes.back()->getParent()->getParent();
299 // To avoid having to handle incoming arguments specially, we lower each arg
300 // to a copy instruction in the entry block. This ensures that the argument
301 // value itself cannot be live across the entry block.
302 BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
303 while (isa<AllocaInst>(AfterAllocaInsertPt) &&
304 isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
305 ++AfterAllocaInsertPt;
306 for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
308 const Type *Ty = AI->getType();
309 // Aggregate types can't be cast, but are legal argument types, so we have
310 // to handle them differently. We use an extract/insert pair as a
311 // lightweight method to achieve the same goal.
312 if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) {
313 Instruction *EI = ExtractValueInst::Create(AI, 0, "",AfterAllocaInsertPt);
314 Instruction *NI = InsertValueInst::Create(AI, EI, 0);
316 AI->replaceAllUsesWith(NI);
317 // Set the operand of the instructions back to the AllocaInst.
318 EI->setOperand(0, AI);
319 NI->setOperand(0, AI);
321 // This is always a no-op cast because we're casting AI to AI->getType()
322 // so src and destination types are identical. BitCast is the only
324 CastInst *NC = new BitCastInst(
325 AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
326 AI->replaceAllUsesWith(NC);
327 // Set the operand of the cast instruction back to the AllocaInst.
328 // Normally it's forbidden to replace a CastInst's operand because it
329 // could cause the opcode to reflect an illegal conversion. However,
330 // we're replacing it here with the same value it was constructed with.
331 // We do this because the above replaceAllUsesWith() clobbered the
332 // operand, but we want this one to remain.
333 NC->setOperand(0, AI);
337 // Finally, scan the code looking for instructions with bad live ranges.
338 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
339 for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
340 // Ignore obvious cases we don't have to handle. In particular, most
341 // instructions either have no uses or only have a single use inside the
342 // current block. Ignore them quickly.
343 Instruction *Inst = II;
344 if (Inst->use_empty()) continue;
345 if (Inst->hasOneUse() &&
346 cast<Instruction>(Inst->use_back())->getParent() == BB &&
347 !isa<PHINode>(Inst->use_back())) continue;
349 // If this is an alloca in the entry block, it's not a real register
351 if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
352 if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
355 // Avoid iterator invalidation by copying users to a temporary vector.
356 SmallVector<Instruction*,16> Users;
357 for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
359 Instruction *User = cast<Instruction>(*UI);
360 if (User->getParent() != BB || isa<PHINode>(User))
361 Users.push_back(User);
364 // Scan all of the uses and see if the live range is live across an unwind
365 // edge. If we find a use live across an invoke edge, create an alloca
366 // and spill the value.
367 std::set<InvokeInst*> InvokesWithStoreInserted;
369 // Find all of the blocks that this value is live in.
370 std::set<BasicBlock*> LiveBBs;
371 LiveBBs.insert(Inst->getParent());
372 while (!Users.empty()) {
373 Instruction *U = Users.back();
376 if (!isa<PHINode>(U)) {
377 MarkBlocksLiveIn(U->getParent(), LiveBBs);
379 // Uses for a PHI node occur in their predecessor block.
380 PHINode *PN = cast<PHINode>(U);
381 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
382 if (PN->getIncomingValue(i) == Inst)
383 MarkBlocksLiveIn(PN->getIncomingBlock(i), LiveBBs);
387 // Now that we know all of the blocks that this thing is live in, see if
388 // it includes any of the unwind locations.
389 bool NeedsSpill = false;
390 for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
391 BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
392 if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
397 // If we decided we need a spill, do it.
400 DemoteRegToStack(*Inst, true);
405 bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
406 SmallVector<ReturnInst*,16> Returns;
407 SmallVector<UnwindInst*,16> Unwinds;
408 SmallVector<InvokeInst*,16> Invokes;
410 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
411 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
412 // Remember all return instructions in case we insert an invoke into this
414 Returns.push_back(RI);
415 } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
416 Invokes.push_back(II);
417 } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
418 Unwinds.push_back(UI);
421 if (Unwinds.empty() && Invokes.empty()) return false;
423 NumInvokes += Invokes.size();
424 NumUnwinds += Unwinds.size();
426 // TODO: This is not an optimal way to do this. In particular, this always
427 // inserts setjmp calls into the entries of functions with invoke instructions
428 // even though there are possibly paths through the function that do not
429 // execute any invokes. In particular, for functions with early exits, e.g.
430 // the 'addMove' method in hexxagon, it would be nice to not have to do the
431 // setjmp stuff on the early exit path. This requires a bit of dataflow, but
432 // would not be too hard to do.
434 // If we have an invoke instruction, insert a setjmp that dominates all
435 // invokes. After the setjmp, use a cond branch that goes to the original
436 // code path on zero, and to a designated 'catch' block of nonzero.
437 Value *OldJmpBufPtr = 0;
438 if (!Invokes.empty()) {
439 // First thing we need to do is scan the whole function for values that are
440 // live across unwind edges. Each value that is live across an unwind edge
441 // we spill into a stack location, guaranteeing that there is nothing live
442 // across the unwind edge. This process also splits all critical edges
443 // coming out of invoke's.
444 splitLiveRangesLiveAcrossInvokes(Invokes);
446 BasicBlock *EntryBB = F.begin();
448 // Create an alloca for the incoming jump buffer ptr and the new jump buffer
449 // that needs to be restored on all exits from the function. This is an
450 // alloca because the value needs to be live across invokes.
451 unsigned Align = TLI ? TLI->getJumpBufAlignment() : 0;
453 new AllocaInst(JBLinkTy, 0, Align,
454 "jblink", F.begin()->begin());
456 Value *Idx[] = { Constant::getNullValue(Type::getInt32Ty(F.getContext())),
457 ConstantInt::get(Type::getInt32Ty(F.getContext()), 1) };
458 OldJmpBufPtr = GetElementPtrInst::Create(JmpBuf, &Idx[0], &Idx[2],
460 EntryBB->getTerminator());
462 // Copy the JBListHead to the alloca.
463 Value *OldBuf = new LoadInst(JBListHead, "oldjmpbufptr", true,
464 EntryBB->getTerminator());
465 new StoreInst(OldBuf, OldJmpBufPtr, true, EntryBB->getTerminator());
467 // Add the new jumpbuf to the list.
468 new StoreInst(JmpBuf, JBListHead, true, EntryBB->getTerminator());
470 // Create the catch block. The catch block is basically a big switch
471 // statement that goes to all of the invoke catch blocks.
472 BasicBlock *CatchBB =
473 BasicBlock::Create(F.getContext(), "setjmp.catch", &F);
475 // Create an alloca which keeps track of the stack pointer before every
476 // invoke, this allows us to properly restore the stack pointer after
478 AllocaInst *StackPtr = new AllocaInst(Type::getInt8PtrTy(F.getContext()), 0,
479 "stackptr", EntryBB->begin());
481 // Create an alloca which keeps track of which invoke is currently
482 // executing. For normal calls it contains zero.
483 AllocaInst *InvokeNum = new AllocaInst(Type::getInt32Ty(F.getContext()), 0,
484 "invokenum",EntryBB->begin());
485 new StoreInst(ConstantInt::get(Type::getInt32Ty(F.getContext()), 0),
486 InvokeNum, true, EntryBB->getTerminator());
488 // Insert a load in the Catch block, and a switch on its value. By default,
489 // we go to a block that just does an unwind (which is the correct action
490 // for a standard call).
491 BasicBlock *UnwindBB = BasicBlock::Create(F.getContext(), "unwindbb", &F);
492 Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBB));
494 Value *CatchLoad = new LoadInst(InvokeNum, "invoke.num", true, CatchBB);
495 SwitchInst *CatchSwitch =
496 SwitchInst::Create(CatchLoad, UnwindBB, Invokes.size(), CatchBB);
498 // Now that things are set up, insert the setjmp call itself.
500 // Split the entry block to insert the conditional branch for the setjmp.
501 BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
504 Idx[1] = ConstantInt::get(Type::getInt32Ty(F.getContext()), 0);
505 Value *JmpBufPtr = GetElementPtrInst::Create(JmpBuf, &Idx[0], &Idx[2],
507 EntryBB->getTerminator());
508 JmpBufPtr = new BitCastInst(JmpBufPtr,
509 Type::getInt8PtrTy(F.getContext()),
510 "tmp", EntryBB->getTerminator());
511 Value *SJRet = CallInst::Create(SetJmpFn, JmpBufPtr, "sjret",
512 EntryBB->getTerminator());
514 // Compare the return value to zero.
515 Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
516 ICmpInst::ICMP_EQ, SJRet,
517 Constant::getNullValue(SJRet->getType()),
519 // Nuke the uncond branch.
520 EntryBB->getTerminator()->eraseFromParent();
522 // Put in a new condbranch in its place.
523 BranchInst::Create(ContBlock, CatchBB, IsNormal, EntryBB);
525 // At this point, we are all set up, rewrite each invoke instruction.
526 for (unsigned i = 0, e = Invokes.size(); i != e; ++i)
527 rewriteExpensiveInvoke(Invokes[i], i+1, InvokeNum, StackPtr, CatchSwitch);
530 // We know that there is at least one unwind.
532 // Create three new blocks, the block to load the jmpbuf ptr and compare
533 // against null, the block to do the longjmp, and the error block for if it
534 // is null. Add them at the end of the function because they are not hot.
535 BasicBlock *UnwindHandler = BasicBlock::Create(F.getContext(),
537 BasicBlock *UnwindBlock = BasicBlock::Create(F.getContext(), "unwind", &F);
538 BasicBlock *TermBlock = BasicBlock::Create(F.getContext(), "unwinderror", &F);
540 // If this function contains an invoke, restore the old jumpbuf ptr.
543 // Before the return, insert a copy from the saved value to the new value.
544 BufPtr = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", UnwindHandler);
545 new StoreInst(BufPtr, JBListHead, UnwindHandler);
547 BufPtr = new LoadInst(JBListHead, "ehlist", UnwindHandler);
550 // Load the JBList, if it's null, then there was no catch!
551 Value *NotNull = new ICmpInst(*UnwindHandler, ICmpInst::ICMP_NE, BufPtr,
552 Constant::getNullValue(BufPtr->getType()),
554 BranchInst::Create(UnwindBlock, TermBlock, NotNull, UnwindHandler);
556 // Create the block to do the longjmp.
557 // Get a pointer to the jmpbuf and longjmp.
558 Value *Idx[] = { Constant::getNullValue(Type::getInt32Ty(F.getContext())),
559 ConstantInt::get(Type::getInt32Ty(F.getContext()), 0) };
560 Idx[0] = GetElementPtrInst::Create(BufPtr, &Idx[0], &Idx[2], "JmpBuf",
562 Idx[0] = new BitCastInst(Idx[0],
563 Type::getInt8PtrTy(F.getContext()),
565 Idx[1] = ConstantInt::get(Type::getInt32Ty(F.getContext()), 1);
566 CallInst::Create(LongJmpFn, Idx, "", UnwindBlock);
567 new UnreachableInst(F.getContext(), UnwindBlock);
569 // Set up the term block ("throw without a catch").
570 new UnreachableInst(F.getContext(), TermBlock);
572 // Insert a call to abort()
573 CallInst::Create(AbortFn, "",
574 TermBlock->getTerminator())->setTailCall();
577 // Replace all unwinds with a branch to the unwind handler.
578 for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
579 BranchInst::Create(UnwindHandler, Unwinds[i]);
580 Unwinds[i]->eraseFromParent();
583 // Finally, for any returns from this function, if this function contains an
584 // invoke, restore the old jmpbuf pointer to its input value.
586 for (unsigned i = 0, e = Returns.size(); i != e; ++i) {
587 ReturnInst *R = Returns[i];
589 // Before the return, insert a copy from the saved value to the new value.
590 Value *OldBuf = new LoadInst(OldJmpBufPtr, "oldjmpbufptr", true, R);
591 new StoreInst(OldBuf, JBListHead, true, R);
598 bool LowerInvoke::runOnFunction(Function &F) {
599 if (useExpensiveEHSupport)
600 return insertExpensiveEHSupport(F);
602 return insertCheapEHSupport(F);